1、Rapid Prototyping and manufacturingIntroductionThe term “rapid prototyping” (RP is a relatively new expression for the generation of three-dimensional models manufactured without the need for machining or products designed on a computer aided design system, the first rapid prototyping system was int

2、roduced on to the US market in 1988 and gave the engineer the opportunity to produce 3 dimensional objects directly from Computer Aided Design (CAD date and succeed in the cost-effective production of patterns and moulds with complex surfaces.The principle advantages of using this technology are:Hig

3、h speed at which the solid model is generated.The complexity of the model does not form any limitation to its production.The early use of these models was to assist the designer in determining fitness and form. It also provided the sales team with a 3 dimensional object to show to a prospective cust

4、omer, this being far better than the traditional orthographic drawing which many people find difficult to interpret.The benefits of RP:1.Converts 3D CAD images into accurate physical models at a fraction of the cost of traditional methods.2.Improves design communication and helps eliminate design mi

5、stakes.3.Reduces “time to market” for a new product.4.Can be used as a powerful marketing tool since the prototype can be seen rather than the drawing.5.The development of this technology has reached into many of the traditional fields, attracting the interest of artisans whose skill any knowledge h

6、as led to 3-D objects being used directly and indirectly as patterns and model for soft tooling.6.Production of models by machining has a number of limitations.7. Material removed during forming is difficult to reclaim.8.Machining in the form of drilling turning milling spark erosion etc., is limite

7、d by the shapes it can produce.9.In the event of design change, conventional tooling such as patterns ,core boxes, dies, jigs etc. ,become expensive to alter ,and in many cases, may require complete re-manufacture. What RP&M CAN DO?To substantially shorten the time for developing patterns, mould

8、s, and prototypes, some manufacturing enterprises have started to use rapid prototyping methods for complex patterns making and component prototyping. Over the past few years, a variety of new rapid manufacturing technologies, generally called Rapid Prototyping and Manufacturing(RP&M,have emerge

9、d ;the technologies developed include Stereo lithography (SL, selected laser sintering(SLS,fused deposition modeling(FDM,laminated object manufacturing(LOM,and three dimensional printing (3D Print.They have a common important feature ;the prototype part is produced by adding materials rather than re

10、moving materials. This simplifies the 3D part producing processes to 2D layer adding processes so that a part can be produced directly from its computer model.rapid prototyping differs with conventional manufacturing methods by adding material layerby layer until the desired sharp is achieved, immed

11、iately reducing or avoiding the loss of material. THE BASIC PROCESS IN RPRP machines process CAD data by slicing the computer model into layers ,each layer being typically 0.1-0.25mm thick the machine then uses this data to construct the model layer by layer ,each layer being bonded to the previous

12、until a solid object is formed. Due to this laminated method of construction a stepped surface is developed on curved faces, the removal of which is essential if maximum advantage of the process is to be realized. Schematic representation of the stepped construction, which requires post processing,

13、is on the above Figure8.1.DEVELOPMENTMore recent developments have been prompted by problems caused by the expansion of the model where it is used as a disposable pattern (like the wax pattern in the lost wax process, Where the resin model is produced t o form solid walls, expansion during the “burn

14、ing-out” stage weakens the ceramic shell, and can cause failure in the firing and/or casting stages.The company, 3D System GmbH, has developed a machine and software, which together allow for the model to be constructed in the form of a honeycomb. The honeycomb structure collapses in on itself durin

15、g “burning-out” thus avoiding the problems of expansion. Each pocket of the honeycomb structure is connected to its neighbor by a small hole that allows for the uncured resin to be drained prior using.Other methods of producing tooling directly from the rapid prototype-such as metal spraying are als

16、o being developed, and this seems to have potential in the production of less complex parts, although it is inevitable that some detail will be lost.Prototyping Company ARRK EUROPE LTD, London, has developed a thin layer technology, which removes many of the inaccuracies inherent in mechanical finis

17、hing. It claims to be the first company in the world to achieve 0.05mm layer build accuracy.ARRKs development team used a combination of subtle mechanical alterations to setting up of its four stereo lithography (SL rapid prototyping machines and proprietary techniques to over come de-wetting. It al

18、so called upon its knowledge of resins.THE BASIC PROCESS IN RPRP machines process CAD data by slicing the computer model into layers ,each layer being typically 0.1-0.25mm thick the machine then uses this data to construct the model layer by layer ,each layer being bonded to the previous until a sol

19、id object is formed. Due to this laminated method of construction a stepped surface is developed on curved faces, the removal of which is essential if maximum advantage of the process is to be realized. Schematic representation of the stepped construction, which requires post processing, is on the a

20、bove Figure8.1.Using this new technology, the company is now able to produce extremely accurate high-quality master parts and tooling. With 0.05mm layer, the build is more precise and all but eliminates the stair-stepping effect. In addition, the need for finishing is dramatically reduced. As a resu

21、lt, the process is ideal for switches, electronic components or any finely details part. Current Application Areas of RP&MDesign Engineering(1 VisualizationWith RP&M, the prototype of a complex part can be built in short time, therefore engineers canevaluate a design very quickly, for it isn

22、t difficult to visualize exactly what the actual complex product will look like.(2 Verification and optimizationImproving product quality is always an important issue of manufacturing. An RP&M prototype can be produced quickly without substantial tooling and labor cost. As a result, the product

23、quality can be improved within the limited time frame and with affordable cost.(3 IterationWith RP&M technology, it is possible to go through multiple design iterations within a short time and substantially reduce the model development time.ManufacturingWe can use the RP&M prototype for prod

24、uctively studies. By providing a physical product at an earlier design stage, we can speed up process planning and tooling design. In addition, by accurately describing complex geometry, the prototype can help reduce problems in interpreting the blue prints on the shop floor. It can also be used in

25、tooling development for mould and master pattern for castings.MarketingTo assist product sales, a prototype can be used to demonstrate the concept, design ideas, as well as the companys ability to produce it. The rea lity of the physical model illustrates the feasibility of the design. Also, the pro

26、totype can be used to gain customs feedback for design modification so that the final product will meet customs requirement.快速成型和生產(chǎn)介紹快速成型這個(gè)術(shù)語是對(duì)于不通過機(jī)器和工具的三維造型生產(chǎn)而產(chǎn)生的一種新的相關(guān)的表示.通過快速生產(chǎn)的準(zhǔn)確能力,用電腦設(shè)計(jì)系統(tǒng)幫助切實(shí)的造型的設(shè)計(jì)生產(chǎn),第一個(gè)快速成型的系統(tǒng)于1988年在美國(guó)的市場(chǎng)內(nèi)被引進(jìn)并且給工程師一個(gè)通過CAD 來設(shè)計(jì)三維實(shí)物的機(jī)會(huì)且成功的生產(chǎn)出復(fù)雜表面的模型.使用這項(xiàng)技術(shù)的操作優(yōu)勢(shì)如下:固態(tài)模型的高速產(chǎn)生.這個(gè)模型的復(fù)

27、雜性對(duì)于生產(chǎn)不能形成任何的限制.最早使用這些模型是用來幫助設(shè)計(jì)者決定形狀和適當(dāng)性.它也能提供給預(yù)期的顧客展示三維實(shí)物的銷售群,這將遠(yuǎn)遠(yuǎn)優(yōu)于那些很多人發(fā)現(xiàn)很難去解釋的傳統(tǒng)直角作圖.快速成型的好處:1.一小部分傳統(tǒng)方法的價(jià)值是把準(zhǔn)確的物理模型轉(zhuǎn)化成三維影象.2.改進(jìn)設(shè)計(jì)的訊息幫助刪除設(shè)計(jì)的錯(cuò)誤.3.對(duì)于新的產(chǎn)品減短上市的時(shí)間.4.自從原形相比做圖更能被理解后它就能作為一種強(qiáng)有力的工具.5.這技術(shù)的發(fā)展到達(dá)了入許多傳統(tǒng)領(lǐng)域,吸引技巧和知識(shí)導(dǎo)致了直接地和間接地使用作為樣式和模型的三維對(duì)象為軟的工具模型。6.模型的生產(chǎn)是通過用機(jī)器制造有一定數(shù)量的限制。7.在成形期間被除去的材料是難回收的。8.用機(jī)器制造

28、以鉆井轉(zhuǎn)動(dòng)的碾碎的火花電蝕等的形式。由它可能導(dǎo)致的形狀限制。9.在設(shè)計(jì)變動(dòng)情形下,常規(guī)鑿出的裝飾例如樣式,核心裝箱,模子,夾具等。變得昂貴而難變更,并且在許多情況下,可以要求完全再制造?？焖俪尚头ㄊ遣煌谝酝ㄟ^增加物質(zhì)層數(shù)的常規(guī)制造方法,直到達(dá)到所期望的銳利程度,立刻減少或避免材料的損失層數(shù)。RP&M能做什么?為開發(fā)的樣式、模子和原型去極大地縮短時(shí)間。一些制造業(yè)企業(yè)開始對(duì)于一些復(fù)雜部件的制造和成型的成分使用快速成型的方法。在過去幾年,各種各樣新的迅速制造業(yè)技術(shù),通常稱為快速成型和制造(RP&M,已經(jīng)涌現(xiàn)了;被開發(fā)的技術(shù)包括立體聲石版印刷(SL,所選擇的激光焊接(SLS,合并的證

29、言塑造(FDM,薄片疊成物體的制造業(yè)(LOM,和3D打印(3D Print。他們有一個(gè)共同的重要特點(diǎn); 原型零件是通過增加材料而不是除去材料導(dǎo)致的。這簡(jiǎn)化3D部分生產(chǎn)過程到增加過程的第2層數(shù),以便零件可以直接地由它的計(jì)算機(jī)模型生產(chǎn)?？焖俪尚偷幕具^程快速成型的機(jī)器是通過切計(jì)算機(jī)模型來制造處理CAD數(shù)據(jù)入層數(shù),每層數(shù)是典型地0.1-0.25毫米厚的機(jī)器然后使用這數(shù)據(jù)一層一層去修建,每一層都將被拈合成以前的樣子直到一個(gè)堅(jiān)實(shí)對(duì)象被形成。由于這個(gè)建筑被碾壓的方法一個(gè)有臺(tái)階的表面在彎曲的表面上被開發(fā),如果過程的最大好處被了解,那么其中是根本的將被撤除,有臺(tái)階建筑的圖示,是要求分步處理的.發(fā)展更多的發(fā)展由與